Conventionally, in the production of semiconductor devices, fine processing by lithography using a photoresist has been performed. The fine processing is a processing method for forming fine convexo-concave shapes corresponding to the following pattern on the surface of a substrate by: forming a thin film of a photoresist on a semiconductor substrate such as a silicon wafer; irradiating the resultant thin film with an active ray such as an ultraviolet ray through a mask pattern in which a pattern of a semiconductor device is depicted for development; and subjecting the substrate to etching processing using the resultant photoresist pattern as a protecting film.
Recently, the high integration of semiconductor devices has progressed and the adopted active ray tends to have a shorter wavelength, such as an ArF excimer laser (193 nm) replacing a KrF excimer laser (248 nm). Due to such a tendency, the influence of reflection of an active ray on a semiconductor substrate has become a large problem. Thus, in order to solve this problem, widely studied is a method of providing an anti-reflective coating (bottom anti-reflective coating) between the photoresist and the substrate.
For such an anti-reflective coating, many investigations on an organic anti-reflective coating composed of a polymer having a light absorbing group and the like are performed due to easiness of its use and so on. Examples thereof include: an acrylic resin-based anti-reflective coating having both a hydroxy group as a crosslinkable group and a light absorbing group within one molecule thereof; and a novolac resin-based anti-reflective coating having both a hydroxy group as a crosslinkable group and a light absorbing group within one molecule thereof.
As a characteristic required for the anti-reflective coating, there can be mentioned having a large absorbance to light or radiation, causing no intermixing with a photoresist (being insoluble in a photoresist solvent), causing no diffusion of low molecule substances from the anti-reflective coating to the photoresist as an upper layer during heating and baking, having a dry etching rate higher than that of the photoresist, and the like.
Furthermore, recently, in order to solve a problem of the wiring delay, which has become apparent as the refinement of a pattern rule of the semiconductor device has progressed, the use of copper as a wiring material has been studied. Along with it, a dual damascene process has been studied as a wiring forming method for the semiconductor substrate. In the dual damascene process, an anti-reflective coating is formed on a substrate which has a large aspect ratio and in which a via hole is formed. Therefore, for the anti-reflective coating used in this process, filling characteristics capable of filling holes without a void, planarization characteristics capable of forming a planar film on the substrate surface, and the like are required.
In addition, as an underlayer film placed between the semiconductor substrate and the photoresist, a film known as a hardmask containing a metal element such as silicon and titanium, is used.
As a method for eliminating an edge hump caused in an edge face of a substrate when the above resist underlayer film is applied onto the substrate, there is disclosed a method for forming an anti-reflective coating containing a fluorine-containing methacrylate polymer or oligomer (see Patent Document 1).